WO1988005232A1 - An optical broadcast network - Google Patents

An optical broadcast network Download PDF

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Publication number
WO1988005232A1
WO1988005232A1 PCT/GB1988/000003 GB8800003W WO8805232A1 WO 1988005232 A1 WO1988005232 A1 WO 1988005232A1 GB 8800003 W GB8800003 W GB 8800003W WO 8805232 A1 WO8805232 A1 WO 8805232A1
Authority
WO
WIPO (PCT)
Prior art keywords
optical
broadcast network
optical transmitter
transmitter
power
Prior art date
Application number
PCT/GB1988/000003
Other languages
French (fr)
Inventor
David Wynford Faulkner
Original Assignee
British Telecommunications Public Limited Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by British Telecommunications Public Limited Company filed Critical British Telecommunications Public Limited Company
Publication of WO1988005232A1 publication Critical patent/WO1988005232A1/en

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/08—Time-division multiplex systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/27—Arrangements for networking
    • H04B10/272—Star-type networks or tree-type networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0682—Clock or time synchronisation in a network by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging

Definitions

  • This invention relates to an optical broadcast network in which optical signals in the form of pulses of light are broadcast over optical fibre transmission paths.
  • optical broadcast networks are used to transmit information at high speed between two nodes and are used to convey large volumes of information.
  • the electro-optic devices which are used as transmitters in such systems usually have the form of semiconductor lasers and are part of sophisticated equipment including control circuitry to control the output of the laser as well as a heat sink and cooling arrangements to prevent the transmitter from overheating.
  • the signal transmitted by such a transmitter may well be a time division multiplex signal so that a large number of different channels of information are transmitted simultaneously over the same optical fibre transmission path but, in this case, all of these channels of information are transmitted by the same optical transmitter.
  • an optical broadcast network comprises a number of remote stations connected to a node by optical fibre transmission paths interconnected by optical power dividers, each remote station including an optical transmitter operating at a high peak power and a low duty cycle.
  • the optical transmitter is enabled to transmit information for only 10% or less of the total time and for a maximum time of 500 ns. This is very much less than conventional optical transmitters which are able to transmit information for 100% of the time but, for, typically 50% of that time are operating to transmit data represented by no pulse of light.
  • the information is transmitted for a maximum time of 250 ns and typically for 60 ns when the power divider has a splitting ratio of 1:128. It is also possible to transmit for periods as short as 0.5 or 1 ns.
  • the optical broadcast network operates an optical time division multiplex system between the node and the number of remote stations with each remote station being enabled to transmit in its own, individual time slot so that the optical signals from the remote stations interleave with one another at the node.
  • One way, and the preferred way, in which the present invention can be used is to operate the optical transmitter at a high peak power many times greater than its maximum continuous power rating but, below its power damage rating under pulsed conditions.
  • the optical transmitter When, for example, the optical transmitter is operating a 10% duty cycle with a short period it is possible for the peak output power to be increased to ten times the maximum continuous power rating for the transmitter whilst still providing only the same thermal dissipation, assuming that the optical transmitter has a linear power to drive current relationship.
  • the optical transmitter is permanently turned ON either it fails catastrophically or a fuse or other protective, element. in series with the device isolates it within a short period of time or its optical output reduces so that it is immediately apparent at the receiving node that a failure has occurred because the output of one transmitter is very low.
  • Another way in which the present invention can be used is for the high peak power at which the optical transmitter of the remote station operates to be the maximum continuous rating of the optical transmitter.
  • Figure 2 is a diagram of part of a second network.
  • the first example represents a conventional time division multiplex transmission system with transmissions from a central controlling node 1 taking place over a first optical fibre transmission line 2 to . an optical power divider 3.
  • the signal power is divided in the divider 3 between N optical fibre transmission lines 4 which lead to N remote stations 5.
  • Information is transmitted continuously over the transmission paths 2 and 4 to all of the remote stations 5 but, as usual in conventional time division multiplex systems, each remote station is enabled to receive only the information transmitted during its own time slot.
  • the remote stations 5 communicate with the controlling node 1 by transmitting over the same optical fibre transmission paths 2 and 4, or alternatively over different optical fibre transmission paths with each remote station 5 being enabled to transmit only during its own predetermined transmission time slot.
  • the maximum time for which each remote station transmitter operates is 1/N of the total time and it may be much less than this.
  • Each remote station 5 transmits information by modulating a sequence of low duty cycle pulses.
  • each node is allocated time slots in which it can transmit modulated low duty cycle pulses and these pulses form a time division multiplex in the optical signal power divider 3 which is received by other nodes on the network.

Abstract

An optical broadcast network comprises a number of remote stations (5) connected to a node (1) by optical fibre transmission paths (2, 4) interconnected by optical power dividers (3), each remote station including an optical transmitter operating at a high peak power and a low duty cycle for a short period. Typically the optical transmitter is enabled to transmit information for only 10 % or less of the total time and for a maximum time of 500 ns.

Description

An optical Broadcast Network
This invention relates to an optical broadcast network in which optical signals in the form of pulses of light are broadcast over optical fibre transmission paths. Usually optical broadcast networks are used to transmit information at high speed between two nodes and are used to convey large volumes of information. The electro-optic devices which are used as transmitters in such systems usually have the form of semiconductor lasers and are part of sophisticated equipment including control circuitry to control the output of the laser as well as a heat sink and cooling arrangements to prevent the transmitter from overheating. The signal transmitted by such a transmitter may well be a time division multiplex signal so that a large number of different channels of information are transmitted simultaneously over the same optical fibre transmission path but, in this case, all of these channels of information are transmitted by the same optical transmitter.
According to this invention an optical broadcast network comprises a number of remote stations connected to a node by optical fibre transmission paths interconnected by optical power dividers, each remote station including an optical transmitter operating at a high peak power and a low duty cycle.
Typically by a low duty cycle the optical transmitter is enabled to transmit information for only 10% or less of the total time and for a maximum time of 500 ns. This is very much less than conventional optical transmitters which are able to transmit information for 100% of the time but, for, typically 50% of that time are operating to transmit data represented by no pulse of light. Preferably the information is transmitted for a maximum time of 250 ns and typically for 60 ns when the power divider has a splitting ratio of 1:128. It is also possible to transmit for periods as short as 0.5 or 1 ns. With an arrangement in accordance with this invention it is preferred that the optical broadcast network operates an optical time division multiplex system between the node and the number of remote stations with each remote station being enabled to transmit in its own, individual time slot so that the optical signals from the remote stations interleave with one another at the node. One way, and the preferred way, in which the present invention can be used is to operate the optical transmitter at a high peak power many times greater than its maximum continuous power rating but, below its power damage rating under pulsed conditions. When, for example, the optical transmitter is operating a 10% duty cycle with a short period it is possible for the peak output power to be increased to ten times the maximum continuous power rating for the transmitter whilst still providing only the same thermal dissipation, assuming that the optical transmitter has a linear power to drive current relationship.
With such an arrangement it is possible to get a substantially constant received signal at the node no matter what splitting ratio is adopted in the optical power dividers by simply increasing the power of the optical transmitter in inverse proportion to the splitting ratio. Also with this arrangement failures can be readily identified. For example, the optical transmitter is permanently turned ON either it fails catastrophically or a fuse or other protective, element. in series with the device isolates it within a short period of time or its optical output reduces so that it is immediately apparent at the receiving node that a failure has occurred because the output of one transmitter is very low. Another way in which the present invention can be used is for the high peak power at which the optical transmitter of the remote station operates to be the maximum continuous rating of the optical transmitter. With this arrangement only a fraction of the normal heat load on the optical transmitter is generated and this reduces the need for a heat sink, allows the optical device to operate at a lower internal temperature at which it is more efficient, and usually eliminates the need for external or internal cooling devices. It also improves the life of the optical transmitter.
Depending upon the application it is possible to arrange for both of these groups of advantages to be gained simultaneously and thus, with a very short duty cycle of, for example, only 1% it would be possible to have an optical transmitter operating at ten times its maximum continuous rating but, at the same time, only dissipate 10% of the heat that it would generate if run continuously at its maximum rating and have its life increased, typically by ten times.
Two particular examples of optical broadcast networks in accordance with this invention will now be described with reference to the accompanying drawings, in which:- Figure 1 is a diagram of a first network; and,
Figure 2 is a diagram of part of a second network.
The first example represents a conventional time division multiplex transmission system with transmissions from a central controlling node 1 taking place over a first optical fibre transmission line 2 to . an optical power divider 3. The signal power is divided in the divider 3 between N optical fibre transmission lines 4 which lead to N remote stations 5. Information is transmitted continuously over the transmission paths 2 and 4 to all of the remote stations 5 but, as usual in conventional time division multiplex systems, each remote station is enabled to receive only the information transmitted during its own time slot. The remote stations 5 communicate with the controlling node 1 by transmitting over the same optical fibre transmission paths 2 and 4, or alternatively over different optical fibre transmission paths with each remote station 5 being enabled to transmit only during its own predetermined transmission time slot. Typically the maximum time for which each remote station transmitter operates is 1/N of the total time and it may be much less than this. Each remote station 5 transmits information by modulating a sequence of low duty cycle pulses.
The second example which is shown in Figure 2 allows each node to broadcast to every other node without the need for common control. Each node is allocated time slots in which it can transmit modulated low duty cycle pulses and these pulses form a time division multiplex in the optical signal power divider 3 which is received by other nodes on the network.

Claims

1. An optical broadcast network comprising a number of remote stations connected to a node by optical fibre transmission paths interconnected by optical power dividers, each remote station including an optical transmitter operating at a high peak power and at a low duty cycle.
2. An optical broadcast network according to claim 1, in which the optical transmitter is enabled to transmit information for substantially 10% or less of the total time and for a maximum time of 500 ns .
3. An optical broadcast network according to claim 2, in which the optical transmitter is enabled to transmit information for a maximum time of substantially 60 ns.
4. An optical broadcast network according to claim 2 or 3, in which the optical transmitter is enabled to transmit information for substantially 1% of the total time.
5. An optical broadcast network according to any one of the preceding claims, in which the optical transmitter operates at a high peak power many times greater than its maximum continuous power rating but, below its instantaneous power damage rating.
6. An optical broadcast network according to any one of claims 1 to 4 in which the high peak power of optical transmitter of the remote station is the maximum continuous rating of the optical transmitter.
7. An optical broadcast network substantially as described with reference to the accompanying drawings. .
PCT/GB1988/000003 1987-01-05 1988-01-05 An optical broadcast network WO1988005232A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8700069 1987-01-05
GB8700069 1987-01-05

Publications (1)

Publication Number Publication Date
WO1988005232A1 true WO1988005232A1 (en) 1988-07-14

Family

ID=10610251

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1988/000003 WO1988005232A1 (en) 1987-01-05 1988-01-05 An optical broadcast network

Country Status (10)

Country Link
US (1) US4975899A (en)
EP (1) EP0276905B1 (en)
JP (1) JPH01502469A (en)
AT (1) ATE95355T1 (en)
AU (1) AU585188B2 (en)
CA (1) CA1314935C (en)
DE (1) DE3884414T2 (en)
ES (1) ES2045095T3 (en)
HK (1) HK135096A (en)
WO (1) WO1988005232A1 (en)

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US5519830A (en) * 1993-06-10 1996-05-21 Adc Telecommunications, Inc. Point-to-multipoint performance monitoring and failure isolation system

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ES2076103B1 (en) * 1993-08-20 1997-10-16 Alcatel Standard Electrica DIGITAL COMMUNICATIONS SYSTEM WITH MULTIPLE ACCESS BY DIVISION IN TIME THROUGH FIBER OPTICS.
US6334219B1 (en) 1994-09-26 2001-12-25 Adc Telecommunications Inc. Channel selection for a hybrid fiber coax network
USRE42236E1 (en) 1995-02-06 2011-03-22 Adc Telecommunications, Inc. Multiuse subcarriers in multipoint-to-point communication using orthogonal frequency division multiplexing
US7280564B1 (en) 1995-02-06 2007-10-09 Adc Telecommunications, Inc. Synchronization techniques in multipoint-to-point communication using orthgonal frequency division multiplexing
US7130541B2 (en) * 2000-10-04 2006-10-31 Wave7 Optics, Inc. System and method for communicating optical signals upstream and downstream between a data service provider and subscriber
US6973271B2 (en) * 2000-10-04 2005-12-06 Wave7 Optics, Inc. System and method for communicating optical signals between a data service provider and subscribers
US7606492B2 (en) 2000-10-04 2009-10-20 Enablence Usa Fttx Networks Inc. System and method for communicating optical signals upstream and downstream between a data service provider and subscribers
WO2003001737A2 (en) * 2000-10-26 2003-01-03 Wave7 Optics, Inc. Method and system for processing upstream packets of an optical network
US7333726B2 (en) * 2001-07-05 2008-02-19 Wave7 Optics, Inc. Method and system for supporting multiple service providers within a single optical network
US6654565B2 (en) 2001-07-05 2003-11-25 Wave7 Optics, Inc. System and method for increasing upstream communication efficiency in an optical network
US7190901B2 (en) * 2001-07-05 2007-03-13 Wave7 Optices, Inc. Method and system for providing a return path for signals generated by legacy terminals in an optical network
WO2003005612A1 (en) * 2001-07-05 2003-01-16 Wave7 Optics, Inc. Methods and systems for providing return path for signals generated by legacy terminals in optical network
US7877014B2 (en) 2001-07-05 2011-01-25 Enablence Technologies Inc. Method and system for providing a return path for signals generated by legacy video service terminals in an optical network
US7529485B2 (en) * 2001-07-05 2009-05-05 Enablence Usa Fttx Networks, Inc. Method and system for supporting multiple services with a subscriber optical interface located outside a subscriber's premises
US7269350B2 (en) * 2001-07-05 2007-09-11 Wave7 Optics, Inc. System and method for communicating optical signals between a data service provider and subscribers
WO2003005611A2 (en) * 2001-07-05 2003-01-16 Wave7 Optics, Inc. System and method for communicating optical signals to multiple subscribers having various bandwidth demands connected to the same optical waveguide
US20030072059A1 (en) * 2001-07-05 2003-04-17 Wave7 Optics, Inc. System and method for securing a communication channel over an optical network
US7146104B2 (en) 2001-07-05 2006-12-05 Wave7 Optics, Inc. Method and system for providing a return data path for legacy terminals by using existing electrical waveguides of a structure
US7593639B2 (en) 2001-08-03 2009-09-22 Enablence Usa Fttx Networks Inc. Method and system for providing a return path for signals generated by legacy terminals in an optical network
US7038910B1 (en) 2002-01-07 2006-05-02 Wave7 Optics, Inc. System and method for removing heat from a subscriber optical interface
US7583897B2 (en) 2002-01-08 2009-09-01 Enablence Usa Fttx Networks Inc. Optical network system and method for supporting upstream signals propagated according to a cable modem protocol
US7623786B2 (en) * 2002-05-20 2009-11-24 Enablence Usa Fttx Networks, Inc. System and method for communicating optical signals to multiple subscribers having various bandwidth demands connected to the same optical waveguide
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US7454141B2 (en) * 2003-03-14 2008-11-18 Enablence Usa Fttx Networks Inc. Method and system for providing a return path for signals generated by legacy terminals in an optical network
US7340180B2 (en) 2004-08-10 2008-03-04 Wave7 Optics, Inc. Countermeasures for idle pattern SRS interference in ethernet optical network systems
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Cited By (2)

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Publication number Priority date Publication date Assignee Title
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US5655068A (en) * 1993-06-10 1997-08-05 Adc Telecommunications, Inc. Point-to-multipoint performance monitoring and failure isolation system

Also Published As

Publication number Publication date
EP0276905B1 (en) 1993-09-29
US4975899A (en) 1990-12-04
AU585188B2 (en) 1989-06-08
AU1088288A (en) 1988-07-27
CA1314935C (en) 1993-03-23
DE3884414D1 (en) 1993-11-04
ATE95355T1 (en) 1993-10-15
ES2045095T3 (en) 1994-01-16
HK135096A (en) 1996-08-02
EP0276905A1 (en) 1988-08-03
DE3884414T2 (en) 1994-03-03
JPH01502469A (en) 1989-08-24

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